At 11:10 AM 5/17/2007 +0100, you wrote:

Well, that probably means you changed the parameter name from "meta" to
"data" in one place but not in the other place.

Please have look over following. Is it right? But the error is same.

<xsl:param name="meta" as="xs:string" required="yes"/>
<xsl:variable name="filename" select="document($meta)" />
<xsl:template match="/">
        <doi>
      <xsl:copy-of select="$filename/doi/text()" />
        </doi>
</xsl:template>